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https://github.com/RGBCube/serenity
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fdfc66db61
This patch adds a vDSO-like mechanism for exposing the current time as an array of per-clock-source timestamps. LibC's clock_gettime() calls sys$map_time_page() to map the kernel's "time page" into the process address space (at a random address, ofc.) This is only done on first call, and from then on the timestamps are fetched from the time page. This first patch only adds support for CLOCK_REALTIME, but eventually we should be able to support all clock sources this way and get rid of sys$clock_gettime() in the kernel entirely. :^) Accesses are synchronized using two atomic integers that are incremented at the start and finish of the kernel's time page update cycle.
137 lines
3.9 KiB
C++
137 lines
3.9 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <AK/Time.h>
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#include <Kernel/Process.h>
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#include <Kernel/Time/TimeManagement.h>
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namespace Kernel {
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KResultOr<FlatPtr> Process::sys$map_time_page()
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{
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VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this);
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REQUIRE_PROMISE(stdio);
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auto& vmobject = TimeManagement::the().time_page_vmobject();
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auto range = address_space().page_directory().range_allocator().allocate_randomized(PAGE_SIZE, PAGE_SIZE);
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if (!range.has_value())
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return ENOMEM;
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auto region_or_error = address_space().allocate_region_with_vmobject(range.value(), vmobject, 0, "Kernel time page"sv, PROT_READ, true);
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if (region_or_error.is_error())
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return region_or_error.error();
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return region_or_error.value()->vaddr().get();
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}
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KResultOr<FlatPtr> Process::sys$clock_gettime(clockid_t clock_id, Userspace<timespec*> user_ts)
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{
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VERIFY_NO_PROCESS_BIG_LOCK(this);
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REQUIRE_PROMISE(stdio);
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if (!TimeManagement::is_valid_clock_id(clock_id))
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return EINVAL;
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auto ts = TimeManagement::the().current_time(clock_id).to_timespec();
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if (!copy_to_user(user_ts, &ts))
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return EFAULT;
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return 0;
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}
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KResultOr<FlatPtr> Process::sys$clock_settime(clockid_t clock_id, Userspace<const timespec*> user_ts)
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{
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VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this);
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REQUIRE_PROMISE(settime);
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if (!is_superuser())
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return EPERM;
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auto ts = copy_time_from_user(user_ts);
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if (!ts.has_value())
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return EFAULT;
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switch (clock_id) {
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case CLOCK_REALTIME:
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TimeManagement::the().set_epoch_time(ts.value());
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break;
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default:
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return EINVAL;
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}
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return 0;
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}
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KResultOr<FlatPtr> Process::sys$clock_nanosleep(Userspace<const Syscall::SC_clock_nanosleep_params*> user_params)
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{
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VERIFY_NO_PROCESS_BIG_LOCK(this);
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REQUIRE_PROMISE(stdio);
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Syscall::SC_clock_nanosleep_params params;
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if (!copy_from_user(¶ms, user_params))
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return EFAULT;
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Optional<Time> requested_sleep = copy_time_from_user(params.requested_sleep);
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if (!requested_sleep.has_value())
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return EFAULT;
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bool is_absolute;
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switch (params.flags) {
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case 0:
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is_absolute = false;
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break;
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case TIMER_ABSTIME:
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is_absolute = true;
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break;
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default:
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return EINVAL;
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}
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if (!TimeManagement::is_valid_clock_id(params.clock_id))
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return EINVAL;
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bool was_interrupted;
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if (is_absolute) {
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was_interrupted = Thread::current()->sleep_until(params.clock_id, requested_sleep.value()).was_interrupted();
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} else {
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Time remaining_sleep;
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was_interrupted = Thread::current()->sleep(params.clock_id, requested_sleep.value(), &remaining_sleep).was_interrupted();
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timespec remaining_sleep_ts = remaining_sleep.to_timespec();
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if (was_interrupted && params.remaining_sleep && !copy_to_user(params.remaining_sleep, &remaining_sleep_ts))
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return EFAULT;
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}
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if (was_interrupted)
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return EINTR;
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return 0;
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}
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KResultOr<FlatPtr> Process::sys$adjtime(Userspace<const timeval*> user_delta, Userspace<timeval*> user_old_delta)
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{
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VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this);
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if (user_old_delta) {
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timespec old_delta_ts = TimeManagement::the().remaining_epoch_time_adjustment();
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timeval old_delta;
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timespec_to_timeval(old_delta_ts, old_delta);
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if (!copy_to_user(user_old_delta, &old_delta))
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return EFAULT;
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}
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if (user_delta) {
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REQUIRE_PROMISE(settime);
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if (!is_superuser())
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return EPERM;
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auto delta = copy_time_from_user(user_delta);
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if (!delta.has_value())
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return EFAULT;
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// FIXME: Should use AK::Time internally
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TimeManagement::the().set_remaining_epoch_time_adjustment(delta->to_timespec());
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}
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return 0;
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}
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}
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